Hydroplane surfboard



Nov. 26, 1963 J. M. KELLY, JR

HYDROPLANE SURFBOARD 2 Sheets-Sheet 1 Filed Sept. 25, 1962 INVENTOR.JOHN M. AEZLZJIZ W MM ATTO/PA/[Vi Nov; 26, 1963 J. M. KELLY, JR

HYDROPLANE SURFBOARD 2 Sheets-Sheet 2 Filed Sept. 25, 1962 INVENTOR JOHNM. KELLZJ/R ATTORNEYS.

United States Patent 3,111,6fi HYDRQPLANE SURFBQARD John M. Kelly, .lr.,4117 liiaelt Point Road,

Honoiuiu, Hawaii Filed Sept. 25, 1962, Ser. No, 226,345 12 (Ilainis.(6!. 9-311?) This invention relates to a surfboard.

Most surfboards now in use are made with curved longitudinal profileswhich rock about their centers of gravity in a manner to aid the riderin maintaining his fore-and-aft balance and to allow the board toapproximate the curvature of the forward slope of the wave. The majordisadvantage in such a rocker construction is that the board drags aquantity of water when moving directionally over and through the waterthereby inhibiting its speed which limitation cannot be overcome by therider. While drag may be desirable when the rider wishes to stall andthus ascend to a higher position on the wave, he also needs maximumspeed capability to shoot the curl, i.e. to plane across the face of thewave, perhaps the most desirable riding maneuver. At any moment, therider may need to stall again or to turn at high speed to avoid hittinganother rider, to avoid rocks or to navigate wind chops or unevenness onthe waves slope.

Other surfboards now designed for use exclusively in big surf, i.e., forwaves above feet in height, are constructed to maximize speed byminimizing the rocker curvature and providing sharp breakaway edgesaround the stern. However, because of their elongated, straight andrelatively flat tails which are adverse to the curved path of thesurfboard when engaged in turning, these boards are inherently incapableof maneuvering at high or low speeds. Thus, these boards sacrificemaneuverability to achieve high speeds whereas the aforementioned rockerboards sacrifice speed for maneuverability.

The primary object of the invention is to overcome the aforementioneddisadvantages resident in the conventional surfboards by combining in asingle surfboard accessibility of both extremely high as well as lowspeeds and increased maneuverability at all speeds. This combination ofheightened functions is accomplished by providing a planing surface anda scorpion tail which are physically differentiated by a transverseshoulder so that the rider, by body movement or shift in weight, canbring the planing surface into partial or full play or bring the draginto effect thereby achieving a wide range of speeds while maintainingmaneuverability throughout.

Another object of the invention is to provide a surfboard which readilyenables the rider to attain a wide range of speeds as well asaccentuated maneuverability at all speeds by the functional coactionbetween a number of features which comprise a pianing surface and ascorpion tail which are differentiated physically by a transverseshoulder thereby creating discreetly separated bottom surfaces, the tailcurving upwardly above the wake and tapering towards its tip away fromthe shoulder to provide a cutaway at the sides of the board in thelocation of the tail. The cutaway, taking advantage of the cleanpartition of the water from the board at the sharp breakaway edge of thetransverse and vertical indentations at the bottom and sides, acts as ameans to prevent the water from being sucked in around the stern andcreate a drag from which the rider cannot release himself. The same istrue for the lift of the tail.

Another object of the invention is to provide a surfboard which enablesthe rider to attain a wide range of speeds, a greater maximum speed, andaccentuated maneuverability, yet the board is relatively simple indesign construction and easier to operate than other models.

These and other objects and features of the invention will become moreapparent as the following description proceeds in conjunction with theaccompanying drawings, wherein:

FIG. 1 is a side elevational view of the surfboard;

FIG. 2 is a bottom plan view thereof;

FIGS. 3, 4 and 5 are fragmentary elevational views of modified forms ofshoulders;

FlG. 6 is a fragmentary top plan view of a modified form of a board atthe location of the shoulder;

FIGS. 7 and 8 are fragmentary bottom views of further modified shoulderconstructions;

FIGS. 9, l0 and 11 are fragmentary enlarged views of the tail end of thesurfboard illustrating respectively low, partial and maximum drag;

FIG. 12 is a fragmentary vertical sectional view through the board justaft of and looking at the shoulder and illustrating one type of sideedge at the planing surface; and

FIG. 13 is a view similar to FIG. 12 illustrating another type of sideedge at the planing surface.

Specific reference is now made to the drawings wherein similar referencecharacters are used for corresponding elements throughout.

The surfboard of the instant invention is generally indicated at lllland is an elongated member capable of being fabricated of a wide varietyof materials, preferably fiberglass-covered air-expanded plastic foam orbalsam wood. The rider engages the upper or deck face 12 while theopposite or bottom face 14 is adapted to engage the water. The bow 16 istapered and preferably upwardly curved to provide a scoop, whereas thestern includes an upwardly curved scorpion tail 18 having a skeg 29depending from its bottom or tail surface 22.

The bottom face 14- includes two separate and distinct surfaces, one thetail surface '22 and the other a planing surface 24 forward thereof.These surfaces are differentiated by providing a transverse shoulder 26formed in the bottom face, which consists of a break in the lines of theside and bottom profiles in such a manner that the tail surface 22 iselevated about the planing surface 24. The depth of the shoulder, i.e.the dis tance by which the tail surface 22 and the planing surface 24are separated, may vary from one-eighth to four inches depending uponthe body weight and preferences of I he riders as to height of the Wavesto be ridden, the degree of slope of the waves at which the higherspeeds are desired and the degree of braking effect desired, the depthof maximum efficiency for all desired capabilities being approximatelyone inch for surfboards averaging eight to ten feet in overall length.Along the longitudinal axis of the surfboard, the location of theshoulder may vary from a point approximately six inches from the sternto a point midway between the bow and stem depending upon the overalllength of the board and the preferences of the riders as to maximumspeed desired, degree of braking effect and sharpness of turningability, the optimum location for desired capabilities beingapproximately twenty-five to thirty inches from the tip of the stern forsurfboards averaging eight to ten feet in overall length.

The transverse line of juncture 28 of the planing surface 24 and theshoulder 26 is a breakaway edge which provides maximum elficiency whenit is sharp, i.e., with a radius of curvature no greater than onethirty-secondth of an inch and when the inclination of the shoulder isclearly differentiated in angle from the horizontal planing surface 24.To provide simplicity of final surfacing in manufacture, as well as toreduce danger of too sharp a breakaway edge, the same may be rounded toa radius of curvature of approximately one-quarter of an inch, as shownat 30 in FIG. 3. It should be understood, however, that a sharperbreakaway edge is functionally preferable due to hydrodynamic action offluids in separating from plane surfaces. The shape of the shoulder asviewed from the side may vary from a deep recess or acute angle as shownin FIGS. 1, 2, 3, 6 and 9-H, through a substantially right angularrecess 32 as shown in FIG. to a shallow recess 34 somewhat in excess ofninety degrees as shown in MG. 4-. The breakaway edge 28 may betransversely curved convexly in the direction of the stern as shown inFIG. 6, instead of straight or concave, to help ease the air around theedge of the shoulder thus enabling more effective release of thescorpion tail from the water;

The planing surface 24 functions at maximum efficiency when it is flat,both transversely and longitudinally, although it may be curved bothlongitudinally and transversely, the degree of longitudinal curvaturebeing least at the shoulder and greatest where the planing surface andbow scoop merge as at 36, see FIG. 1. The side edges of the planingsurface may be rounded as shown at 37 in FIG. 13 to cause the board togroove slightly into the wave but for maximum efliciency they fair downgently from the deck at an angle of approximately forty-five degrees toend in sharp side breakaway edges as shown at 39 in FIG. 12 and whichare substantially parallel to the axis of the surfboard as suggested at3? in FIG. 2. The radius of curvature of each side edge from theshoulder forward a distance approximately equal to the length of theplaning surface, for maximum efficiency, should not exceedonethirty-secondth of an inch, the edge becoming rounded as it mergeswith the rounded sides of the board at the bow end.

The dimensions of the planing surface 24- may vary according to theoverall dimensions of the board and height, weight and individualpreferences of the rider but should be between seventeen and twenty-sixinches transversely, and longitudinally, i.e. from the shoulder 26 tothe scoop point 36, it should comprise approximately one-fifth toone-third of the total bottom surface of the board. The instant boardcan have a straight instead of an uplifted bow, in which case theplaning surface extends from the shoulder forward to the bow extremityof the board thereby comprising a major portion of the total bottomsurface.

The entire section aft of the shoulder is the scorpion tail 18 which iselevated above the planing surface in the manner indicated hereinbeforewith reference to the depth of the shoulder. The scorpion tail is curvedboth longitudinally and transversely and upwardly from the plane of theplaning surface, the upward curvature varying from slightly above theplane to a maximum of approximately eight inches measured from the tipof the tail to the extension of the plane aft of the shoulder.

It will be seen from FIG. 2 that the sides of the scorpion tail curveinwardly or taper in diminishing width fro-m the shoulder to the tip ofthe tail to provide a cutaway 38, which is the space between theextensions aft of the sides of the board beyond the shoulder and thesides of the tail as seen in FIG. 2. The sides of the scorpion tail atthe shoulder may be sharply indented by acute angles 4t as shown in FIG.6 or by right angles 42 as shown in FIG. 7. The sides of the scorpiontail may also be continuous with the curvature of the sides of theboard, as shown at 44 in FIG. 8, though the aforementioned indentationaffords *less drag and greater speed. In either case of indentation orabsence thereof, the scorpion tail should lie within and not exceed thedimension across the wake area as produced by the shoulder, the planingsurface and the maximum width of the surfboard forward of the shoulder.

The edges of the scorpion tail are so curved that tail surface 22 fairsgradually upward to meet the deck surface 12 in a high-drag breakawayedge comprising the periphery of tail is, the radius of curvature beingnot less than one-eighth of an inch at the edge itself but with maximumdrag effect being achieved with a curvai ture of approximately one andone-half to two inches radius.

The skeg 24 should be long enough to extend from approximately two totwelve inches below the line extending aft of the planing surface 24 andcan be positioned at any point from th shoulder to the aft end,depending upon the riders preference as to sharpness of the turningcircle of the board, with maximum efiiciency being achievable forturning at all speeds when the skeg is located from about four to twelveinches measured from the aft end of the board to the aftermost trailingedge of the skeg.

In use, the rider stands on the deck of the board and by leaning hisweight on the forward foot he brings the planing surface 2 5 intopartial play and by taking a stance farther forward brings it into fullplay. By leaning back on the foot placed to the rear, he minimizesplaning and brings the drag into effect. PEG. 9 shows the condition ofthe water 46 at low drag yielding high speed, FIG. 10 shows thecondition at partial drag yielding intermediate speed and FIG. 11 showsthe condition at maximum drag yielding slow speed. The scorpion tailprovides a curvature adapted to the shape of the turning circle whendepressed into the water thus enabling the rider to attain superiorturning capability. The cutaway 38 at the tail enables the water to partcleanly from the sides of the board rather than be sucked in around thestern at all times, as on conventional boards, thereby creating dragfrom which the rider cannot release himself. Thus, with the instantsurfboard, the rider can achieve any degree of speed while maintainingmaneuverability throughout.

While preferred embodiments of the invention have been here shown anddescribed, it will be understood that skilled artisans may make minorvariations without departing from the spirit of the invention and thescope of the appended claims.

I claim:

1. A surfboard comprising an elongated member having a deck and a bottomface, and a vertically and transversely extending shoulder in the bottomface dividing said face into two discreet vertically spaced surfaces,the upper one extending aft of the shoulder to the stern andconstituting a tail surface and the lower one extending forwardly of theshoulder and constituting a planing surface, the portion of the boardaft of said shoulder being a scorpion tail whose sides taper inwardlytowards the stern to provide a cutaway portion between the sides of thetail and extensions of the sides of the board aft of said shoulder.

2. A surfboard comprising an elongated member having a deck and a bottomface, and a vertically and transversely extending shoulder in the bottomface dividing said face into two discreet vertically spaced surfaces,the upper one extending aft of the shoulder to the stern andconstituting a tail surface and the lower one extending forwardly of theshoulder and constituting a planing surface, the portion of the boardaft of said shoulder being a scorpion tail whose sides taper inwardlytowards the stern to provide a cutaway portion between the sides of thetail and extensions of the sides of the board aft of said shoulder, saidforwardly extending surface having an area equal at least to one-ifththat of the total area of the bottom face.

3. A surfboard comprising an elongated member having a deck and a bottomface, and a vertically and transversely extending shoulder in the bottomface dividing said face into two discreet vertically spaced surfaces,the upper one extending aft of the shoulder to the stern andconstituting a tail surface and the lower one extending forwardly of theshoulder and constituting a planing surface, the portion of the boardaft of said shoulder being a scorption tail whose sides taper inwardlytowards the stern to provide a cutaway portion between the sides of thetail and extensions of the sides of the board aft of said shoulder, saidtail curving upwardly from said shoulder to its tip.

4. A surfboard comprising an elongated member having a deck and a bottomface, and a vertically and transversely extending shoulder in the bottomface dividing said face into two discreet vertically spaced surfaces,the upper one extending aft of the shoulder to the stern andconstituting a tail surface and the lower one extending forwardly of theshoulder and constituting a planing surface, the portion of the boardaft of said shoulder being a scorpion tail whose sides taper inwardlytowards the stern to provide a cutaway portion between the sides of thetail and extensions of the sides of the board aft of said shoulder, saidforwardly extending portion being substantially flat and having an areaequal at least to onefifth that of the total area of the bottom face,said tail curving upwardly from said shoulder to its tip.

5. A surfboard comprising an elongated member having a deck and a bottomface, and a vertically and transversely extending shoulder in the bottomface dividing said face into two discreet vertically spaced surfaces,the upper one extending aft of the shoulder to the stern andconstituting a tail surface and the lower one extending forwardly of theshoulder and constituting a planing surface, the portion of the boardaft of said shoulder being a scorpion tail whose sides taper inwardlytowards the stern to provide a cutaway portion between the sides of thetail and extensions of the sides of the board aft of said shoulder, saidshoulder forming a sharp breakaway edge at its juncture with saidplaning surface, said tail curving upwardly from said shoulder to itstip.

6. A surfboard comprising an elongated member having a deck and a bottomface, and a vertically and transversely extending shoulder in the bottomface dividing said face into two discreet vertically spaced surfaces,the upper one extending aft of the shoulder to the stern andconstituting a tail surface and the lower one being substantially flat,extending forwardly of the shoulder and constituting a planing surface,the portion of the board aft of said shoulder being a scorpion tailwhose sides taper inwardly towards the stern to provide a cutawayportion between the sides of the tail and extensions of the sides of theboard aft of said shoulder, said shoulder forming a sharp breakaway edgeat its juncture with said planing surface, said tail curving upwardlyfrom said shoulder to its tip, the sides of said board at the locationof said planing surface fairing downwardly from the deck to terminate insharp breakaway edges along said planing surface.

7. A surfboard comprising an elongated member having a deck and a bottomface, and a vertically and transversely extending shoulder in the bottomface dividing said face into two discreet vertically spaced surfaces,the upper one extending aft of the shoulder to the stern andconstituting a tail surface and the lower one extending forwardly of theshoulder and constituting a planing surface, the portion of the boardaft of said shoulder being a scorpion tail whose sides taper inwardlytowards the stern to provide a cutaway portion between the sides of thetail and extensions of the sides of the board aft of said shoulder, saidtail curving upwardly from said shoulder to its tip, and a skegdepending from said tail surface and terminating below said planingsurface.

8. A surfboard comprising an elongated member having a deck and a bottomface, a vertically and transversely extending shoulder formed in thebottom face at a predetermined location dividing the same into twodiscreet vertically spaced continuous surfaces, the upper one extendingaft of the shoulder and constituting a tail surface, the lower one beingsubstantially fiat and extending forwardly of said shoulder andconstituting a planing surface, the portion of the board aft of saidshoulder being a scorpion tail which curves upwardly from said shoulderto its tip and whose sides taper inwardly from said shoulder to its tipto provide a cutaway portion between the sides of said tail andextensions of the sides of the board aft of said shoulder, a skegdepending from said tail surface and terminating below said planingsurface, and an upwardly curved bow portion, forwardly of said planingsurface, the area of said planing surface from said shoulder to its lineof merger with said bow portion comprising at least one-fifth that ofthe total area of said bottom face.

9. A surfboard comprising an elongated member having a deck and a bottomface, a vertically and transversely extending shoulder formed in thebottom face at a predetermined location dividing the same into twodiscreet vertically spaced continuous surfaces, the upper one extendingaft of the shoulder and constituting a tail surface, the lower one beingsubstantially fiat and extending forwardly of said shoulder andconstituting a planing surface, the portion of the board aft of saidshoulder being a scorpion tail which curves upwardly from said shoulderto its tip and whose sides taper inwardly from said shoulder to its tipto provide a cutaway portion between the sides of said tail andextensions of the sides of the board aft of said shoulder, a skegdepending from said tail surface and terminating below said planingsurface, and an upwardly curved bow portion forwardly of said planingsurface, the area of said planing surface from said shoulder to its lineof merger with said bow portion comprising at least one-fifth that ofthe total area of said bottom face, said shoulder forming a sharpbreakaway edge at its juncture with said planing surface, the sides ofsaid board at the location of said planing surface fairing downwardlyfrom the deck to terminate in sharp breakaway edges along said planingsurface, the tapered sides of said tail fairing upwardly from said tailsurface to terminate in rounded edges along said tail.

10. A surfboard comprising an elongated member having a deck and abottom face, a vertically and transversely extending shoulder formed inthe bottom face at a predetermined location dividing the same into twodiscreet vertically spaced continuous surfaces, the upper one extendingaft of the shoulder and constituting a tail surface, the lower oneextending forwardly of said shoulder and constituting a planing surface,the portion of the board aft of said shoulder being a scorpion tailwhich curves upwardly from said shoulder to its tip and whose sidestaper inwardly from said shoulder to its tip to provide a cutawayportion between the sides of said tail and extensions of the sides ofthe board aft of said shoulder, a skeg depending from said tail surfaceand terminating below said planing surface, and an upwardly curved bowportion forwardly of said planing surface, the area of said planingsurface from said shoulder to its line of merger with said bow portioncomprising at least onefifth that of the total area of said bottom face,the degree of longitudinal curvature of said planing surface being leastat said shoulder and greatest where it merges with said bow portion.

11. A surfboard comprising an elongated member having a deck and abottom face, and a vertically and transversely extending shoulder in thebottom face dividing said face into two discreet vertically spacedsurfaces, the upper one extending aft of the shoulder to the stern andconstituting a tail surface and the lower one extending forwardly of theshoulder and constituting a planing surface, the portion of the boardaft of said shoulder being a scorpion tail whose sides taper inwardlytowards the stern to provide a cutaway portion between the sides of thetail and extensions of the sides of the board aft of said shoulder, saidshoulder forming a sharp breakaway edge at its juncture with saidplaning surface, said tail curving upwardly from said shoulder to itstip, the sides of said board at the location of said planing surfacebeing rounded to cause the board to groove slightly into the wave.

'12. A surfboard comprising an elongated member having a deck and abottom face, and a vertically and trans- T2 versely extending shoulderin the bottom face dividing said face into two discreet verticallyspaced surfaces, the upper one extending aft of the shoulder to thestern and constituting a tail surface and the lower one extendingforwardly of the shoulder and constituting a planing surface, theportion of the board aft of said shoulder being a scorpion tail whosesides taper inwardly towards the stern to provide a cutaway portionbetween the sides of the tail and extensions of the sides of the boardaft of said shoulder, said shoulder forming a sharp breakaway edge atits juncture with said planing surface, said tail curving upwardly fromsaid shoulder to its tip, said breakaway edge being transversely curvedconvexly towards the stern. References Cited in the file of this patentUNITED STATES PATENTS

1. A SURFBOARD COMPRISING AN ELONGATED MEMBER HAVING A DECK AND A BOTTOM FACE, AND A VERTICALLY AND TRANSVERSELY EXTENDING SHOULDER IN THE BOTTOM FACE DIVIDING SAID FACE INTO TWO DISCREET VERTICALLY SPACED SURFACES, THE UPPER ONE EXTENDING AFT OF THE SHOULDER TO THE STERN AND CONSTITUTING A TAIL SURFACE AND THE LOWER ONE EXTENDING FORWARDLY OF THE SHOULDER AND CONSTITUTING A PLANING SURFACE, THE PORTION OF THE BOARD AFT OF SAID SHOULDER BEING A SCORPION TAIL WHOSE SIDES TAPER INWARDLY TOWARDS THE STERN TO PROVIDE A CUTAWAY PORTION BETWEEN THE SIDES OF THE TAIL AND EXTENSIONS OF THE SIDES OF THE BOARD AFT OF SAID SHOULDER. 